Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A conventional navigation device may provide route guidance by finding the current location of the device using the Global Positioning System (GPS), and by determining a route from the current location to a destination based on maps stored in a storage device, such as a DVD or a disk drive. The current location and the route guidance may be displayed on the screen of the device. When a conventional navigation device is installed in a vehicle, the screen of the device may be placed in the control panel of the vehicle or attached to the windshield of the vehicle. A driver is often unable to look at the in-vehicle screen of the navigation device while still paying full attention to the road ahead.
A conventional navigation device may also employ a voice guidance system to inform a driver to turn at an intersection or exit a highway. When two roads or intersections are located very close to each other, the navigation device may not distinguish these roads or intersections, and the voice guidance may only provide ambiguous information such as “make a left turn soon.” As a result, the driver may have to take his/her eyes off the road in order to further examine the map supported by the navigation device.